Well after fitting the FFD during the week I can confirm that it has made absolutely no difference to the noise or operation of the injectors and I have also confirmed that the noise is infact the actual opening and closing of them rather than them touching against the TB's etc etc...
After recently changing the cambelt, tensioner, idler, water pump and replacing all the tappets I can confirm that the engine is running like a dream and is as quiet as a mouse.
However, this has just inflamed the problem of excessively noisey injectors as they are no longer drowned out by rest of the engine.
I'm wondering if it could stem from a wiring problem to the ECU, i.e. not a good enough - or + feed maybe?
Normally I would learn to live with it but the noise was not present when the same setup was in the Cavalier which makes me think that something is not as it should be.
Any info or ideas anyone may have are greatly welcomed.